Generally speaking, doors and windows essentially comprise:                a fixed frame;        a mobile frame, or sash in the case of tilt and turn units, slidably connected or hinged to the fixed frame;        a control handle mounted on one of the vertical members of the mobile frame;        at least one rod segment slidably mounted in a groove made in the vertical member and connected to, and controlled by, the control handle (in some cases, where there is a traditional handle, the connection is obtained by drive elements constituting accessories of the rod) in such a way as to slide in both directions in the groove to define at least one open configuration and one closed configuration of the door or window;        closing means associated with, and protruding from, the operating rod (to define additional accessories of the rod) and designed to oppose or engage respective fixed abutment means located on the vertical member of the fixed frame in order to define the closed configuration.        
More specifically, the accessories may comprise, for the drive means, two facing protrusions or tabs or two bosses forming a space occupied by the handle lever to permit transmission of the motion produced by turning the handgrip of the handle and thus displacing the rod in the groove.
The closing means, on the other hand, may be embodied by pins or bosses and catches (in the case of sliding doors/windows) stably associated with the rod.
As is known, these drive and closing elements are applied to the operating rod by connecting means consisting of: a socket made in the central section of the rod (half way along the width of the rod) and a suitable bottom portion of these elements housed in the socket and locked in place preferably by plastic deformation of the material the bottom portion of the element is made of or by caulking.
Examples of these applications are disclosed in document EP 1.454.708 (in the name of the same Applicant as this invention) as regards an example of a drive boss, in documents EP 1.132.169 and EP 1.460.216 (also both in the name of the same Applicant as this invention) as regards the above mentioned pins or bosses, and in Italian patent applications BO2007A000444 and BO2007A000445 (also in the name of the same Applicant as this invention) as regards the closing catches for sliding doors and windows which, in one of these cases, is locked to the rod by means of the specially shaped bottom portion of an element or pin.
These connecting means, very practical for positioning the accessories and quick to apply, have been shown to have one drawback due to poor holding strength over time leading to deterioration of the rod-accessory assembly.
As regards the striker elements, the step of moving the rod to close the door or window, in the case of pins or bosses, comprises sliding the rod along the groove until the boss is laterally or tangentially coupled to a retaining wall of the above mentioned abutment element.
This coupling pushes the boss sideways and produces a force (moment) both on the boss and on the zone where the connecting means are coupled to the rod (usually made of a synthetic material such as polyamide) housed relatively loosely—precisely because it is slidable—in the operating groove: these forces, with repeated use over time, eventually deteriorate the coupling and weaken the join between the rod and the boss and, more seriously still, the area surrounding the rod.
This deterioration reduces the strength of the door or window and, in the more serious cases, causes the rod to break or the boss to be detached from the rod, with obvious problems in terms of door/window security.
Similarly, as regards the above mentioned catch, the coupling to the respective abutment element—first abutting the front inside a socket and then lifting or lowering inside the socket for locking in the closed configuration—produces upwardly or downwardly directed lateral strain, leading to front stresses on the point where the catch and the rod are joined and creating the same problems as those mentioned above for the boss.
As regards the drive elements, one or more protrusions or levers are pushed in onto the tab or boss, producing an upwardly or downwardly directed lateral force (moment) similar to the one mentioned above in connection with the catch, leading to front stresses on the point where the tab and the rod are joined and creating the same problems as those mentioned above for the closing bosses.
In addition to the above, account must also be taken of break-in attempts which not only produce further, contingent strain on the door or window but are also facilitated by existing wear, especially on the closing elements.